Albite (var. moonstone)

Look at these minerals from one direction, then another, to catch the play of light.

Labradorites, moonstones, and sunstones belong to the feldspar family, which makes up over half of the Earth's crust. Occasionally, this common material forms crystals that shimmer like a rainbow on a soap bubble. This iridescence occurs when closely spaced layers in a crystal diffract light, separating it into its component colors.

Look for:

• sunstones flashing golden orange (from flecks of goethite or copper).
• a labradorite crystal with concentric bands of iridescent color.
• moonstones, known for bluish-white iridescence.